Directive antenna system



June 10, 1952 Filed Dec. 31, 1948 FIG.

(PRIOR ART) W. E. KOCK DIRECTIVE ANTENNA SYSTEM FIG. 5

H-PLANE DIRECTIVE PATTERN OFJ'YSTEM 0F FIG 3 TRANSLA T10 05 VI C E 4 Sheets-Sheet 1 FIG. 2

(PRIOR ART) rmn/su T/ON DEV/CE FIG. 6

E-PLAIVE DIRECTIVE PATTERN 0F SYJTEM 0F FIG. .7

DE C/BELI DEGREES' l/VI/ENTOR W E. KOCK ATTORNEY Filed Dec, 51, 1948 TRANSLATION DE VIC E TRANSLA T/OIV DEV/CE 4 Sheets-Sheet 2 /N l/E N TOR W E. KOCK A T TORNE V June 10, 1952 w. E. KocK 2,599,763

DIRECTIVE ANTENNA SYSTEM Filed Dec. 51, 1948 4 Sheets-Sheet 3 FIG. 7

INVENTOR W E. KOCK ATTORNEY June 10, 1952 w KQCK 2,599,763

DIRECTIVE ANTENNA SYSTEM Filed Dec. 51, 1948 4 Sheets-Sheet 4 G 42 4% a 7 By m5. KOCK ATTORNEY Patented June 10, 1952 DIRECTIVE ANTENNA SYSTEM Winston E. Kock, Basking Ridge, N. J., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application December 31, 1948, Serial No. 68,542

8 Claims. (01. 250-33.63)

This invention relates to directive antenna systems and particularly to metallic refractors of the wave guide type for use in such systems.

' This application is a continuation-in-part of my copending application for Radio Relay Systems, Serial No. 5,952, filed February 3, 1948, which matured into United States Patent 2,530,826, granted November 21, 1950.

As is known radio lenses having one or more stepped zones, such as the solid dielectric lenses disclosed in Patent 2,283,935 to A. P. King and in the copending application of A. M. Skellett, Serial No. 717,214, filed December 19, 1946, now 'United States Patent 2,547,416 issued April 3, 1951, and the metallic lenses disclosed in my copending application, Serial No. 642,723, filed J anuary 22, 1946, have been suggested for usev in directive antenna systems. Also, radio reflectors having one or more zones, such as the reflectors disclosed in Patent 1,906,546 to R. H. Darbord have been proposed for use in such systems. In certain of the aforesaid lens systems heretofore utilized the directive action is sometimes impaired by reason of the so-called shadow effect and the diffraction effect at the steps, or zone peripheries, of the lens. The shadow effect, if pronounced, is especially detrimental since it may cause the establishment of large undesired minor lobes. While, as explained on page 26 of my above-mentioned application, Serial No. 642,723, the shadow and diffraction effects of the steps may be reduced somewhat by utilizing intermediate stepping, rather than high or low stepping, it now appears desirable to eliminate the shadow effect in multiple zone lenses of both the circularly symmetrical and cylindrically symmetrical types, in a more complete manner,

than heretofore accomplished.

It is one object of this invention to obtain, in a lens antenna, a directive pattern having negligible minor lobes.

It is another object of this invention to eliminate shadow effects in a stepped cylindrically symmetrical metallic lens.

It is another object to obtain, as a manufacture, a compact, easily constructed compound radio refractor comprising a metallic len and a metallic prism.

In accordance with one embodiment of the invention the first or central zone and the zone adjacent thereto, of a multiple zone cylindrically symmetrical metallic lens, such as that illustrated by Fig. 21 of my above-mentioned application, serial No. 642,723, are separated by a narrow flat metallic plate extending parallel to the optical axis of the lens. An inclined metallic plate is attached to the narrow plate and forms with the narrow plate an obtuse dihedral angle. The inclined plate is included, substantially, in a plane containing the focal line of the lens. Also, a wide fiat metallic plate is positioned between the narrow plate and the longitudinal axis of the front face of the lens. The three plates extend perpendicular to, and intersect, the spaced metallic members forming the lens. In operation, the intermediate lens section included between the wide plate and the two attached plates functions as a sectoral horn, and substantially no shadow effect is produced.

The invention will be more fully understood from a perusal of the following description taken in conjunction with the drawing on which like reference characters denote elements'of similar function and on which: F v v Figs. 1 and 2 are explanatory side views of a metallic lens in which prior art low stepping is' utilized; Figs. 3 and 4 are respectivelyperspective and side views of a directive antenna system comprising a metallic lens constructed in accordance with the invention;

Figs. 5 and 6 are respectively 'H-plane and E- plane directive patterns for the system of Fig. 3

Fig. 7 i a perspective view of another directive antenna system comprising a pair of lenses each' similar to the lens included in the system of Fig. 3;

Fig. 8 is a perspective view of still another di-' rective antenna system comprising a single lens' similar to the lens included in the system of Fig. 3;

Fig. 9 is a perspective view of a compound me'-' tallic refractor constructed in accordance with the invention and'comprising a focussing section and anon-focussing section; and

Figs. 10 and 11 are respectively perspective views and side views of another compound metallic refractor constructed in accordance with the invention.

Referring to Figs. 1 and 2, the cylindrical symmetrical plano-concave metallic lens I comprises a plurality of spaced stepped metallic members or walls, such as the typical wall 2 shown in cross-section. The lens has two zones A and B. a focal line 3, an optical or electromagnet axis a, an elliptically concave back face 5 and a plane front face 6. Reference numeral 1 denotes the longitudinal axis, which intersects the optical axis 4, of the plane front face 6.

The step 8' s between :zones A and B isa full-wave length and is of the fiat or low type extending parallel to the optical axis. Except for the number of zones and the type of stepping, the lens I is the same as that illustrated by Fig. 21 of my copending application, Serial No. 642,723. Numeral 9 denotes a line type antenna, or more specifically, a sectoral horn which is connected by a wave guide ||l to-a translation device I l which may be a transceiver, a transmiter or a receiver. The throat aperture of the sectoral horn 9 is aligned with the focal line 3 of the metallic lens In operation, Fig. 1 assuming the device H is a transmitter and that the electric polarization 2 of the wavelets is parallel to. thewalls 2, the rays I3, emitted by the horn 9 along the radial directions and forming a diverging beam M, are refracted by the lens so as to form a beam l of parallel rays l6. As is apparent from Fig. 1, the step 8 is positioned between thefocal line 3 and a portion of the concave face of zone B, tiiat'isthe step 8.- s a s a p of zone B. so that'the. out o n pa a l b am l5 ntains a hole or null portion l7. As a result, the transmitting E-plane directive pattern may contain a nullgand hence a pronounced minor lobe. Similarlmin reception, Fig. 2, the parallel rays I6 in the portion H of the incoming beam l5, after passing through zone B, are intercepted by the step 8 and hence do not reach the focal line 3 and horn 9, so that the incoming converging beam l4 does not'containthe intercepted energy. This loss in-received energy results in objectionabl m nc lobes.

Referring to Figs. 3 and 4, the. cylindrically symmetrical meta lic pla o-concavelens 2| comprises a, plurality of flat metallic members or walls. 22 ;extending parallel to the electric polar-izationulzandcspaced apart at least one half ofthe operating wavelength, The lens has a cene tra'l; zone. A and an outer zone, B, the stepping betweenizonesbeingsubstantially a wavelength and the curvature of the concave surface of each zone being elliptical, as explained in my copendingapplication Serial No. 642,723. The lens 2| is equipped-with fiat metallic topand bottom plates 23 extending parallel to the longitudinal axis 1 ofithefronti face 6' and the electromagnetic axis Q of thelens; and; each of these plates intersects thee-extremities of the metallic wall members 22. Numeral 24 denotes a flat narrow metallic plate separating zones A and B and numeral 25 designates a fiat wide metallic plate positioned in zone A between the narrow plate 24 and the longitudinal, axis 1 of thefront face 6 of lens 2|. A

fiat inclined metallic plate 26 is attached to the back edge of the narrow plate 24 and forms therewith an obtuse angle. The inclined plate is included in a plane containing the focal line 3 of: lens 2|. All three plates intersect: at right angles the plano-concave plates 22 constituting the lens; 2| and extend parallel to the longitudinal axi's l of thefront face 6:. As is apparent from Fig. 4,.the lens section A2 formed by the wide plate 25 and the two plates 24 and 26, taken together, constitutes in effect a horn section flared in the plane of; electric polarization onEaplane. l2 and not flared in the plane of magnetic polarization or. H-plane.

focal line-3:01 the cylindrical lens 2| is .al gnedwith. the axis ofthe substantially linear andv the flares 3|, the flares 3| being attached .planethe emitted beam is exceedingly narrow in this plane. The cylindrical wave front emanating from the line antenna 28 is converted to. a plane front. by the lens 2| and, by reason of the refractive effect in the E plane I2 of the lens 2|, the bearnoutgoing from the system 28, 2| is exceedingly narrow in the E plane. In reception, the converse operation is obtained by reason of the theoremjof reciprocity.

In more detail, zone B, and section. A1, Fig. 4, of zone 'A function asv conventional phase-advance lens sections and section A2 of zone A functions as a phase-advance lens and also as a horn, thatis, the Wave front in section A2 gradually expands. By reason of the presence and orientation ofthe metallic plates'or separators 24 and 26, and thehorn action of section A2, diffraction and shadow effects are substantially eliminated. As shown in Fig. 4, all of the diverging' or converging rays l4 and all of theparallel rays I 6 pass through the lens; 2|, and no portion of either zone A or B-is shadowed by' the; zone stepping.

I t should' be pointed out here that; in accordance. with the'invention, metallic; separators corresponding; to flat plate 25; maybe included between the Z'Oflfisofi a circularly symmetrical lens. having a; point'ic us f r the. p rp se-of. p venting shadow efiects. In the case of a circularly-symmetrical: lens the inclined plate, correspending; torthe plate 2 6, has a conical shape.

Figs. 5- and; '6. illustrate-.respectivelythe:measured Heplane and E-planedirective patterns of. system-constructed in. accordance with Figs. 3 and- 4- 'As shown on the drawing the-majorlobes 3;| of: the I-I-planeand E-plane patterns arerelatively-narrow; the widths; taken 'at the half power of three-decibel point; of the H-planemajor l'obe, and'the' F-plane major lobebeing respectively 1:.25; and'3.6f degrees. Also, by reason: of the factthat the separators. 24, 25 and 25 function to eliminate. diffraction and shadow effects, the patterns'of Figs. 5 and 6 do not include a large "shadow" minor lobe, and the actual minor lobes- 32 ofeach pattern are more than twenty decibels below-themajor lobe and'therefore negligible.

Fig. '7 illustrates a double lens, system for securing; an E-plane major lobehalf power width which is smaller than that shown' ,in'the pattern of Fig. 6' and comparable to'theiH-plane major lobe half power width shown in the pattern of Fig. 5. In the system of FigFTthet focal line 3 .of-a small cylindricallysymmetrical lens 33 constructed. in accordance with the invention is aligned with the longitudi'nalaxis of the'linear:

. 34', also constructed-in.accordance withthe in.-

vention, is aligned with longitudinal axis 1 of the front face 6 of-the small lens'33. In the H- plane, parallel tothe focal line 3, the directive pattern for the system 28, 33 and 34 is essentially the same as that of'the: system of Fig. 3. In: the

E plane containing the polarization l2, the small lens 33 converts the circular wave front emanating from the orifice 21 to a linear front. This linear front, however, appears to be circular rather than linear at a point remote from lens 33, such as the location of lens 34. The lens 34 changes this circular front to a linear front, whereby the directive action in the E plane is enhanced. In reception, in the E plane the large lens 34 focusses the waves on the axis 1 of the small lens 33 and the small lens 33 refocusses the waves on the longitudinal axis of the orifices 21 of the feed antenna 28.

The antenna system 35 of Fig. 8 comprises a cylindrical lens 2| constructed in accordance with the invention, a half pill-box feed antenna 36, and a horn 31 connecting the lens 2| and the orifice of the half pill-box 36. The horn 31 is flared in the E plane and comprises the flared metallic side members 38 and the nonflared metallic side members 39. As shown on the drawing, one of the two parallel plate members of the pill-box antenna 36 extends around the edge of the other parallel plate member and the half pill-box is positioned on, or folded back upon, one of the wide horn walls 39, whereby the orifice of the half pill-box faces the lens 2| and the pill-box extends towards the lens 2!. As in the systems of Figs. 3 and 7, the open end of guide It! is positioned at the focal line of the short parabolic reflector included in the half pill-box. As is believed to be apparent from the description of Fig. 3, in operation, the system produces a major lobe having a narrow width in the E plane and a narrow width in the H plane, the minor lobes in both planes being in significant. The shields or horn sides enhance the directive effect and also prevent interference from undesired waves.

Figs. 9 and 10 illustrate compound refractors which are especially suitable for use in relay systems such as that disclosed in my copending application of which the present application is a continuation in part. The refractor '40, Fig. 9,. comprises a focussing section or piano-concave lens 4|, such as that disclosed and claimed in my above-mentioned copending application Serial No. 642,723, and a non-focussing or prism section 42 such as that disclosed in my copending application Serial No. 642,722, filed January 22, 1946, now Patent No. 2,588,249, issued March 4, 1952. Each section comprises a plurality of spaced metallic plates 43 and each plate is com mon to both sections so that, while from an electrical or refractive standpoint, the two sections are distinct, the two sections are not distinct considered from a mechanical or physical standpoint. The plates are held in position by the wooden members 44. In the embodiment of Fig. 10, the prism section 42 is in a sense included between two thin plano-concave lenses 45 and 46, as more clearly shown in Fig. 11.

In operation, Fig. 9, the lens 4| functions to convert the cylindrical front 4'! originating at the line focus 3 to a plane front having a propagation direction 48 and the prism section functions to change the direction of propagation from direction 48 to direction 49. Similarly, in the system of Figs. 10 and 11, the lens section 45 operates to convert the cylindrical wave front plate shaped toconform to a zone contour line of said refractor, said plate being included between and completely separating two of said stepped zones.

2. An electromagnetic wave metallic lens for focussing waves having a given electric polarization, said lens comprising an assembly of a plurality of plane metallic walls extending parallel to said polarization and spaced apart uniformly in a direction perpendicular to said polarization one set of edges of said metallic walls being linear and being included in and defining a plane surface, said plane surface having a longitudinal axis, the opposite set of edges of said metallic walls being concave and stepped and being included in and defining a stepped cylindrically concave surface, the variation of the distance between said one set of edges and said opposite set of edges, in the direction of polarization, being proportioned to focus a plane wave, impinging perpendicularly upon said plane surface, along a focal line spaced from and on the concave side of said assembly, said stepped concave surface having a central zone and a stepped zone adjacent thereto, a flat metallic plate included between and completely separating said zones and intersecting said walls.

3. A lens in accordance with claim 2, and another flat metallic plate extending parallel to said first-mentioned plate, said other plate intersecting said metallic walls and positioned between said longitudinal axis and the first-menticned flat metallic plate.

4. .A lens, in accordance with claim 2, and another fiat metallic plate attached to said firstmentioned plate and forming therewith an obtuse dihedral angle, said other plate being included in a plane containing said focal line, substantially.

5. A cylindrically symmetrical rectangular electromagnetic wave metallic lens for focusing waves having a given electric polarization, said lens having a focal line, said lens comprising a plurality of metallic walls extending parallel to said polarization and spaced apart uniformly in a direction perpendicular to said polarization one set of edges of said metallic walls being linear and being included in and defining a plane surface, said plane surface having a longitudinal axis, the opposite set of edges of said metallic walls being concave and stepped and being included in and defining a stepped cylindrically concave surface, said concave surface having a central zone and a stepped zone adjacent thereto, a first flat metallic plate included between and completely separating said zones and intersecting said walls, a second flat metallic plate extending parallel to said first plate, said second plate intersecting said metallic walls and positioned between said first plate and the longitudinal axis of said front plane surface, and a third flat metallic plate attached to the said first plate and forming therewith, an obtuse di- I hedral, angle, said-third plate being-included in edges and a pair of long edges, the focal line of saidlens being aligned with the longitudinal axis of said orifice, a horn comprising a pair of flared side members and a pair of non-flared side members, said pair of flared horn side members extendingfrom the pair of short edges of said orifice, respectively, to the outermost left and right metallic walls of said lens, respectively, and said pair'of non-flared horn side members eX tending from the upper and lower long edges of said orifice, respectively, to the upper and lower sets of ends of said plurality of metallic walls, respectively, of said lens, whereby said lens is positioned at the mouth orifice of said horn.

8. In combination, a first and a second cylindrically symmetrical metallic lens each constructed in accordance with claim 5, a line antenna having a substantially linear orifice and comprisinga, cylindrical parabolic reflectorhaving a focal: line, a wave guide connectedlto ra translationdeviceand havingan aperture at saidfocal line of said reflector, the first lens being positioned between the second lens and said line antenna, the front plane surfaces of both lenses facing away from said reflector, the focal line of the second lens being-aligned with the longitudinal axisrof the front plane surface of the. first lens-and the focal line, of the first lens being aligned with the longitudinal axis of said linear orifice.

WINSTON E. K061i.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,206,683 Wolfl July 2, 1940 2,283,935 King May 26, 1942 2,405,242 Southworth Aug. 5, 1946 2,405,992 Bruce Aug. 20, 1946 2,411,872 Feldman Dec. 3, 1946 2,425,488 Peterson et a1. Aug. 12, 194! 2,4l2,95l Iams June 8, 1948 2,508,479 Wheeler May 23, 1950 OTHER REFERENCES Proc, 1. R:- E., vol. pages 328 to 836, Noveni. ber 1946. 

